When you're looking out over acres larger than a suburban, quarter-acre lot, there is an outsized chance of error. It's just not good enough that the current owner points to a property line "between that tree and that creek bottom." If the real estate sheet says 25 acres, you want to know the property is 25 acres and within what boundaries.

"Just because the deed says 25 acres does not mean it's there between the recognized boundaries," Richardson says.

Technology gives you the opportunity before closing the deal to know your boundaries almost exactly. But you should also know that a new survey might be slightly different from the original just because surveyors now use GPS systems and lasers, rather than tree lines and fenceposts as markers.

"I can only say it's important to get a survey, and it's important to have it done not just by a licensed surveyor. Do some research, and get the best in the county," Richardson advises. "When a survey is done properly, there's a lot of deed research, knowledge and groundwork that goes into producing that survey map."

Unfortunately, surveys are not always conducted prior to the sale of rural acreages. "Of the last four properties I've sold," says Chris Martin of Runyan Realty in Paris, Ill., "I think two had a survey. The majority of homes in rural America, or at least rural Illinois, don't get surveyed."

It's not because of money that surveys are not done. A thorough survey costs upward of $1,000. That's not prohibitive, given the money involved in an acreage purchase. And if the sale involves a lender, a survey will be required.

The survey uncovers encroachment issues such as a misplaced fenceline. This, and other issues, are best resolved—and less expensively fixed—before closing. Tackling survey problems later means both court time and lawyers.

Or worse, there may be nothing you can do. Most states recognize some aspects of what is generally known as "adverse possession." It's a legal act in which your property can fall into the possession of your neighbor if you fail to assert your property rights.

An example might be a man who built fences 30 years ago on land you assume is about to be yours. Even if the survey draws attention to the discrepancy, there may be nothing you can do. Just make sure you are not paying for that piece of property in the sale or in subsequent property taxes.